Real experiences with pre-order

First time ordering a dress from Reformation. I'm a little skeptical because it was a 'pre-order'. I did notice that before finalizing the purchase but it'd taken me hours to decide the dress I wanted & I'm on a tight deadline with delivery, wedding is on the 22nd. I guess my question is how accurate is the 'pre-order expected to ship by Aug 7th' ? Do they ship it on time usually? How''s yalls experience with pre-orders? Thank u :)